Permittivity less than 1

[Grumpy]

What is the significance of space with a permittivity less than 1?

Speed of light becomes faster than "c"

What else?

[bte]

Would that cause an EM doppler effect in the region < 1?

[Reiyuki]

What is the significance of space with a permittivity less than 1?

Speed of light becomes faster than "c"

What else?

While I do not like resurrecting dead threads, this was way too juicy to let go.
All of the cool sci-fi stuff seems to start happening at permittivity <1.


Lets assume a bubble of <1 permitivity space:

Dielectric isolation:
Because permittivity is a function of dielectricity, voltage/charge would be less likely to migrate across the bubble, and tending to conserve charge inside the bubble.


Radio signal compression:
Radio transmissions entering this bubble would be up-shifted (low-frequency signals from outside would be shifted up in frequency as they enter the bubble, and be shifted down as they leave the bubble.  A hypothetical signal of 1khz in normal space could appear as 1mhz inside the bubble.

This lets us exploit Shannon–Hartley bandwidth/information law, because now we can now pack 1mhz transmissions into what would appear in normal space to be a 1khz carrier.  IE: encoding more data in a carrier than would normally be possible in regular space alone.

(I am unsure what the transmission velocity of these waves would be, but I suspect that the EM wave packet is conserved by stretching whilst retaining its own >C velocity.)


Refraction:
Due to the upshift, waves approaching the bubble an angle would experience a negative refraction index, and would be largely bent around the bubble. 
This would make that region of space largely invisible to microwaves at low excitation and largely invisible to visible light at high excitation.


Gravity/inertia:
In order to conserve energy under E=MC^2, the apparent mass of objects inside the bubble will have to decrease opposite to the velocity of light.
Because of this, the mass and inertia of anything inside the bubble must decrease proportional to the increase in C.


Rate-of-time:
The rate of time changes inside the bubble change would appear identical to gravitational time dilation (I think).  Objects inside the bubble might experience 1 minute while the outside world experiences several hours.



Follow-up questions:
There are probably even more effects that have yet to be considered....

Now the follow-up question to all this is, what means do we have of altering the permittivity of free space electrically? (pulsed opposed magnetic fields and high voltage impulses would be the logical first lines of experimentation.)

And the second question would be, is how could we design experiments to detect this change in permittivity of space (LC circuits, crystal oscillators, accelerometers, fiber optic delay-lines, spectroscopic measurement, refraction lensing?)

[F6FLT]

What is the significance of space with a permittivity less than 1?

Speed of light becomes faster than "c"

What else?

By "permittivity less than 1" I presume you mean relative permittivity: ε_r=ε(ω)/ε₀.
The speed of light in a dielectric is v = 1/√(ε*µ). ε_r<1 implies ε<ε₀ but doesn't imply v>c, it depends also on µ.

ε is defined as D/E, in the same way that µ is defined as B/H. With ε_r<1, then D<E: the dielectric reacts  to an electric field less than the vacuum.
The interesting case is when ε<0. This means that D opposes the electric field E, that the force between electrons becomes attractive and so on. A capacitor with such a dielectric would mean that i= -C dV/dt: the "discharge" of the capacitor would produce a current, the capacitor becomes a source of energy.

Negative ε exists in some materials for a certain frequency range (for instance in metals at optic frequencies) but it is not simple because ε is a complex. At zero frequency, it seems that's theoretically possible to have ε<0, but none has been reported. That's what we would need for the capacitor.
We can also imagine that if ε<0, then energy must be expended to produce it, in the same way as we ensure negative resistance by polarizing it at the right point on its V-I curve.

[Grumpy]

I had the idea that the permittivity and permeability of space are not "constant".

I also suspect that UFO's create fields that alter the permittivity and permeability of the space around them.

[Reiyuki]

Composite Medium with Simultaneously Negative Permeability and Permittivity (at a specific frequency)
https://journals.aps.org/prl/pdf/10.1103/PhysRevLett.84.4184